A treatment of a number of medical conditions requires the placement of catheters in a patient's blood vessel for an extended period time. These long-term applications include blood access for hemodialysis, chemotherapy, parental nutrition, blood transfusions and blood sampling.
It is well known in the medical field that chronic placement of a catheter in a patient's blood vessel often results in catheter failure due to many reasons. Thrombus formation at the tip of the catheter is one of the reasons. According to many medical journal articles, thrombus formation at the tip of the catheter is related to the structural design of a catheter.
Current hemodialysis catheters are used to filter blood in the superior vena cava (SVC). Typically, they have two lumens. One is the arterial lumen which is used to aspirate blood which travels to the dialysis machine; another is the venous lumen which ejects the filtered blood into the SVC and then heart and lungs, and the rest of the body. Traditionally the arterial lumen is always the proximal lumen and the venous lumen is always the distal lumen. This is done to prevent recirculation, where previously filtered and newly ejected blood is sucked back in and re-filtered by the machine. Depending on the tip design, the vacuum created at the proximal arterial opening can sometimes draw the catheter against the SVC wall, thereby occluding the opening, lowering the flow rate, and preventing dialysis from taking place. Accordingly, many hemodialysis catheters provide the proximal lumen with one or more additional side ports to mitigate occlusion of the proximal opening.
To prevent thrombus from forming inside the catheter between uses, a so-called heparin lock is used where the catheter is flushed with heparin and clamped off so that the normal inside volume of the catheter is occupied by heparin. However, side ports on the proximal lumen of the catheter can prevent the effectiveness of heparin or other anticoagulants because heparin can leak out of the sideports leaving catheter shaft distal to the sideports unprotected. Many medical articles point to hemodialysis side ports as being a cause for thrombus and fibrous sheath formation, this lowers blood flow rates and makes the catheter non-functional.
Accordingly, it is desired to provide a catheter with thrombus blocker that can easily and effectively remove and/or prevent the thrombus forming at the tip of the catheter.